lisp/master.el

   1 ;;; master.el --- make a buffer the master over another buffer
   2
   3 ;; Copyright (C) 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008
   4 ;;   Free Software Foundation, Inc.
   5
   6 ;; Author: Alex Schroeder <alex@gnu.org>
   7 ;; Maintainer: Alex Schroeder <alex@gnu.org>
   8 ;; Version: 1.0.2
   9 ;; Keywords: comm
  10
  11 ;; This file is part of GNU Emacs.
  12
  13 ;; GNU Emacs is free software: you can redistribute it and/or modify
  14 ;; it under the terms of the GNU General Public License as published by
  15 ;; the Free Software Foundation, either version 3 of the License, or
  16 ;; (at your option) any later version.
  17
  18 ;; GNU Emacs is distributed in the hope that it will be useful,
  19 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  20 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  21 ;; GNU General Public License for more details.
  22
  23 ;; You should have received a copy of the GNU General Public License
  24 ;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
  25
  26 ;;; Commentary:
  27
  28 ;; master-mode is a minor mode which enables you to scroll another
  29 ;; buffer (the slave) without leaving your current buffer (the master).
  30
  31 ;; It can be used by sql.el, for example: The SQL buffer is the master
  32 ;; and its SQLi buffer is the slave.  This allows you to scroll the SQLi
  33 ;; buffer containing the output from the SQL buffer containing the
  34 ;; commands.
  35 ;;
  36 ;; This is how to use sql.el and master.el together: The variable
  37 ;; sql-buffer contains the slave buffer.  It is a local variable in the
  38 ;; SQL buffer.
  39 ;;
  40 ;; (add-hook 'sql-mode-hook
  41 ;;         (function (lambda ()
  42 ;;                     (master-mode t)
  43 ;;                     (master-set-slave sql-buffer))))
  44 ;; (add-hook 'sql-set-sqli-hook
  45 ;;         (function (lambda ()
  46 ;;                     (master-set-slave sql-buffer))))
  47
  48 ;;; Thanks to all the people who helped me out:
  49 ;;
  50 ;; Rob Riepel <networking.stanford.edu>
  51
  52 ;;; History:
  53 ;;
  54
  55 ;;; Code:
  56
  57 (defgroup master nil
  58   "Support for master/slave relationships between buffers."
  59   :version "22.1"
  60   :group 'convenience)
  61
  62 ;; Variables that don't need initialization.
  63
  64 (defvar master-of nil
  65   "Slave buffer of the current buffer.  See `master-mode'.
  66 You can set this variable using `master-set-slave'.")
  67
  68 (defvar master-set-slave-hook nil
  69   "Hook run after the slave is changed using \\[master-set-slave].")
  70
  71 ;;; Define master mode.
  72
  73 ;;;###autoload
  74 (define-minor-mode master-mode
  75   "Toggle Master mode.
  76 With no argument, this command toggles the mode.
  77 Non-null prefix argument turns on the mode.
  78 Null prefix argument turns off the mode.
  79
  80 When Master mode is enabled, you can scroll the slave buffer using the
  81 following commands:
  82
  83 \\{master-mode-map}
  84
  85 The slave buffer is stored in the buffer-local variable `master-of'.
  86 You can set this variable using `master-set-slave'.  You can show
  87 yourself the value of `master-of' by calling `master-show-slave'."
  88   :group 'master
  89   :keymap
  90   '(("\C-c\C-n" . master-says-scroll-up)
  91     ("\C-c\C-p" . master-says-scroll-down)
  92     ("\C-c<" . master-says-beginning-of-buffer)
  93     ("\C-c>" . master-says-end-of-buffer)
  94     ("\C-c\C-l" . master-says-recenter)))
  95
  96 ;; Initialize Master mode by setting a slave buffer.
  97
  98 (defun master-set-slave (buffer)
  99   "Makes BUFFER the slave of the current buffer.
 100 Use \\[master-mode] to toggle control of the slave buffer."
 101   (interactive "bSlave: ")
 102   (make-local-variable 'master-of)
 103   (setq master-of buffer)
 104   (run-hooks 'master-set-slave-hook))
 105
 106 (defun master-show-slave ()
 107   "Displays a message with the name of the slave buffer."
 108   (interactive)
 109   (message "This buffer is the master of %s.  Master-mode is %S."
 110            (or master-of "none")
 111            master-mode))
 112
 113 \f
 114
 115 ;;; Functions that the master buffer can call for the slave buffer.
 116
 117 (defun master-says-scroll-up (&optional arg)
 118   "Display and scroll the slave buffer up.
 119 See `scroll-up'."
 120   (interactive)
 121   (master-says 'scroll-up arg))
 122
 123 (defun master-says-scroll-down (&optional arg)
 124   "Display and scroll the slave buffer down.
 125 See `scroll-down'."
 126   (interactive)
 127   (master-says 'scroll-down arg))
 128
 129 (defun master-says-beginning-of-buffer (&optional arg)
 130   "Display and move to the beginning of the slave buffer.
 131 See `beginning-of-buffer'."
 132   (interactive)
 133   (master-says 'beginning-of-buffer arg))
 134
 135 (defun master-says-end-of-buffer (&optional arg)
 136   "Display and move to the end of the slave buffer.
 137 See `end-of-buffer'."
 138   (interactive)
 139   (master-says 'end-of-buffer arg))
 140
 141 (defun master-says-recenter (&optional arg)
 142   "Recenter the slave buffer.
 143 See `recenter'."
 144   (interactive)
 145   (master-says 'recenter arg))
 146
 147 ;; The master function doing the stuff.
 148
 149 (defun master-says (&optional command arg)
 150   "Display slave buffer and execute COMMAND with ARG in its window."
 151   (interactive)
 152   (if (null (buffer-live-p (get-buffer master-of)))
 153       (error "Slave buffer has disappeared")
 154     (let ((window  (selected-window)))
 155       (if (not (eq (window-buffer window) (get-buffer master-of)))
 156           (switch-to-buffer-other-window master-of))
 157       (if command (condition-case nil (apply command arg) (error nil)))
 158       (select-window window))))
 159
 160 (provide 'master)
 161
 162 ;; arch-tag: dca08daa-8127-45ae-b77e-b135160dce98
 163 ;;; master.el ends here